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Biomedical subjects

L Friedman

Publications and source records attributed to L Friedman.

At least 199 records · Page 11Linked to original sources
PubMed1990

Learning mnemonics: roles of aging and subtle cognitive impairment.

Previously validated methods of memory training were used in conjunction with the Folstein Mini-Mental State Examination (MMSE) to explore the relationship between complexity of learned mnemonic, aging, and subtle cognitive impairment. Subjects were 218 community-dwelling elderly. Treatment included imagery mnemonics for remembering names and faces and lists. There was a significant interaction among age, type of learning task (face-name vs. list), and improvement when controlling for MMSE score. There was also a significant interaction among MMSE score, type of learning task, and improvement when controlling for age. Scores on the more complex list-learning mnemonic were more affected by age and MMSE scores than were scores on the face-name mnemonic. Implications of the findings for cognitive training of the old old and the impaired are discussed.

Aged↗
PubMed1990

gamma-Aminobutyric acidA receptor regulation in culture: altered allosteric interactions following prolonged exposure to benzodiazepines, barbiturates, and methylxanthines.

In previous reports, we have described the use of primary neuronal cultures derived from chick brain to study the regulation of the gamma-aminobutyric acidA (GABAA) receptor complex. Chronic exposure of cultures to GABA, benzodiazepines, or methylxanthines results in decreased enhancement of [3H]flunitrazepam binding by GABA, consistent with an allosteric uncoupling of GABA and benzodiazepine recognition sites of the GABAA receptor. In the present communication, we extend our studies of the pharmacology of benzodiazepine- and methylxanthine-induced uncoupling of GABA/benzodiazepine recognition site interactions and present evidence to show that certain barbiturates (barbital and pentobarbital) also induce uncoupling. Chronic exposure to flurazepam (a high efficacy benzodiazepine) elicits no change in the number of benzodiazepine binding sites or the affinity of benzodiazepine binding in the absence of GABA. Whereas flurazepam and theophylline decrease coupling, Ro15-1788 (a low efficacy benzodiazepine) inhibits flurazepam-induced but not theophylline-induced uncoupling, suggesting that theophylline and flurazepam act through separate receptors. Flurazepam-induced uncoupling is not prevented by SR-95531 or picrotoxin (specific inhibitors of GABA action) and, therefore, is not an indirect effect mediated by endogenous GABA. The onset of flurazepam-induced uncoupling (EC50 approximately 1 microM) exhibits a t 1/2 of about 18 hr, in general agreement with the half-time for receptor turnover. Uncoupling is reversible following washout and recovery at 37 degrees. These results are discussed in terms of mechanisms of GABAA receptor regulation in response to chronic exposure to functionally homologous or heterologous ligands.

1-Methyl-3-isobutylxanthine↗
PubMed1990

Coronal computed tomography.

The authors describe a method of direct coronal computed tomography (CT) of the body for infants and children who are introduced onto the gantry in a lateral decubitus position transversely across the examination table. Scans are planned from a lateral scout view, with the number of coronal scans ranging from four to six. Images are more informative and detail is sharper than routine axial cuts with coronal reformations. This method is valuable in resolving complex problems related to disease adjacent to the diaphragm and can accurately demonstrate the extension and relation of lesions to neighboring structures.

Hernia, Diaphragmatic↗
PubMed1990

Computed tomography of wrist trauma.

We devised a rapid and sensitive computed tomography (CT) method to assess the acutely injured wrist, healing carpal fractures and post-traumatic osteonecrosis, when the plain films offer insufficient information. The wrist is positioned in a simple reverse-L-shaped Perspex immobilizer. With the scaphoid as the center of the arc and the long axis of the distal radius as the reference 0 degrees line, sequential coronal scans of the wrist were done in 10 degrees increments in an arc of 40 degrees to give 0 degrees, 10 degrees, 20 degrees, 30 degrees and 40 degrees scans. The 0 degrees and 10 degrees arc scans were best for evaluating the distal radius and ulna and soft tissues, the 10 degrees and 20 degrees scans for the carpal bones other than the scaphoid, and their relation to each other, the 30 degrees and 40 degrees scans, parallel to the long axis of the scaphoid, for fractures of the scaphoid and the hook of the hamate. In addition the 40 degrees scan offered an excellent carpal tunnel view. In 22 patients examined for wrist trauma CT was found to be more accurate than plain films and plain-film tomography in determining the presence of a fracture (4 scaphoid and 1 distal radius), in assessing the degree of osseous union (12) and in evaluating intercarpal fusion (2). In addition CT detected avascular necrosis of the lunate in two patients and erosions of the scaphoid and distal radius attributed to rheumatoid arthritis in one.

Carpal Bones↗
PubMed1989

Facilitated micromethod for measurement of metabolically generated 14CO2, with application to measurement of ornithine decarboxylase.

A modified microassay for the determination of metabolically generated 14CO2 is described and is applied to the measurement of ornithine decarboxylase in animal tissue preparations. In this technique, the reaction takes place in a microcentrifuge tube inside a 20-ml scintillation vial that also contains a center well with a CO2-trapping agent. The vial is sealed with a silicone septum-lined plastic screw cap. After the initial incubation period during which the enzymatic reaction occurs, acid is injected through the septum into the reaction tube, and 14CO2 is released during a second incubation period. The reaction vial is then removed, counting solution is added to the scintillation vial, and radioactivity is measured. Linearity is present with respect to both increasing amounts of tissue and incubation time. Recovery of evolved 14CO2 was greater (97.5 vs 91.5%) and variation between replicate samples was less (coefficient of variation 2.7 vs 8.5%) when the modified microassay was compared with an assay system that requires removal of the screw cap from the vial before acid injection. The modification allows greater safety and facilitated assays, which could result in savings of both time and laboratory personnel. Special precautions for the use of NaH14CO3 as the recovery marker are noted.

Animals↗
PubMed1989

Induction of ornithine decarboxylase in the stomach mucosa of swine with NaCl or 12-O-tetradecanoylphorbol-13-acetate.

The effect of sodium chloride and 12-O-tetradecanoylphorbol-13-acetate on ornithine decarboxylase (ODC) activity in gastric mucosa of miniature swine was investigated as a model for gastric inflammation. The level of the enzyme was lower in the pylorus than in the fundic or cardiac regions of the stomach in untreated animals. Treatment with sodium chloride at 1 g/kg produced large increases in all three regions, with the greatest relative increase in the pylorus. Treatment with sodium chloride at 0.25 g/kg or the phorbol ester at 2.0 mg/pig produced significant but less dramatic increases. ODC activity in control and treated mucosal extracts was inhibited by the specific ODC inhibitor difluoromethylornithine. Most of the enzyme activity was associated with superficial and exfoliated cells that could be scraped from the mucosal surface. No increase in the inflammatory mediator leukotriene B4 was observed in the mucosal extracts. Ornithine decarboxylase appears to be a useful enzymatic marker for the regenerative events that occur after tissue damage and may correlate with the putative tumor-promoting function of sodium chloride in gastric tissues.

Animals↗
PubMed1989

Benign histiocytic fibroma of rib with CT correlation.

Benign fibrous histiocytoma is a benign tumor with fibroblastic and histiocytic differentiation, most commonly found in soft tissues and less frequently in adult bones. It is identical histologically to non-ossifying fibromas of childhood but differs in its clinical and radiological features. We here report a 26-year-old woman with benign histiocytic fibroma in a rare location, a rib, with computed tomographic correlation. Such correlation has not been reported previously.

Adult↗
PubMed1989

Hartmann's "Ego Psychology and the Problem of Adaptation".

Hartmann's monograph is an argument for the problem-solving value of all aspects of the mind and for the subordination of intelligence to the organism's larger, primarily social purposes. Hartmann proposed that, in psychoanalytic treatment, intelligent reflection serves one's largest purposes by taking respectful account of non-rational but adaptive ways of appraising reality, with a view toward making the best use of non-rational as well as rational propensities. He regarded it as the kind of thinking that the sociologist, Karl Mannheim, had recommended to government planners faced with immensely complicated, incompletely masterable forces. Hartmann's view of the role of the intellect in analytic treatment suggests that therapists should maintain both their demand for intelligent reflection and their hopefulness about other kinds of work that may be going on sub rosa.

Adaptation, Psychological↗
PubMed1988

Recording of movement-related potentials from the human cortex.

A patient with intractable epilepsy secondary to a brain tumor was evaluated with a chronically implanted array of 64 stainless-steel subdural electrodes covering the perirolandic area. Cortical potentials associated with voluntary, self-paced middle-finger extension were recorded simultaneously from subdural and scalp electrodes using a computer-assisted method for averaging movement-related potential (MRP) in relation to electromyographic (EMG) onset. A high-amplitude negative potential, Bereitschaftspotential/negative slope (BP/NS'), preceding the onset of the EMG activity by more than 1 sec was recorded in an extremely localized fashion exclusively from electrodes placed in the precentral hand motor area as well as in the more medial part of the somatosensory hand area. These results suggest that the hand motor and sensory areas have an essential participation in the generation of MRPs and, therefore, also in the preparation of voluntary finger movements.

Adult↗
PubMed1988

Apparent ornithine decarboxylase activity, measured by 14CO2 trapping, after frozen storage of rat tissue and rat tissue supernatants.

Ornithine decarboxylase (ODC) activity of rat tissues was measured by the standard 14CO2 trapping method after frozen storage (-60 or -70 degrees C) of the tissues or their 105,000g supernatants. True ODC activity was determined by two methods: (a) addition of the inhibitors alpha-difluoromethylornithine (DFMO), a specific irreversible inhibitor of ODC, or aminooxyacetate (AOA), an inhibitor that blocks the decarboxylation of ornithine by mitochondrial enzymes; and (b) chromatographic analysis of the reaction products. In the frozen supernatants of liver and spleen, ODC activity changed only slightly after 1 day but increased 29 and 14%, respectively, by 30 days; activity in kidney supernatant decreased 17% after 1 day and remained near that level at 30 days. Kidney and spleen ODC activity was inhibited 90-100% by DFMO, but apparent liver ODC activity was inhibited only 60-75%. In the supernatant prepared from tissue stored frozen for 1 day, apparent ODC activity in liver increased 500% over that activity in the freshly prepared supernatant; at 23 days, apparent activity increased 755% for liver and 121% for kidney. After 23 days, DFMO did not inhibit apparent ODC activity in supernatants from frozen liver and inhibited ODC in frozen kidney by only 49%. With AOA, the ODC activities of the fresh and frozen supernatants were similar, indicating that the large increase in apparent ODC activity in frozen tissue was due to artifacts from the metabolism of ornithine via the mitochondrial pathway. HPLC analysis of the reaction products resulting from the incubation of uniformly labeled [14C]ornithine with the fresh and frozen preparations indicated no increase in putrescine with the frozen preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminooxyacetic Acid↗
PubMed1988

Studies on the metabolism and toxicity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in cultures of embryonic rat mesencephalon.

The metabolism of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) was studied in dissociated cell cultures prepared from embryonic rat mesencephalon. MPTP was added to the feeding medium and at the end of the incubation period MPTP was separated from the water-soluble metabolite by ether extraction. Our results demonstrate that, in cultures, MPTP is oxidized predominantly by monoamine oxidase B, since deprenyl but not clorgyline had an inhibitory effect on its metabolism. The metabolite of MPTP diffuses freely in the feeding medium (99% of the total) and its concentration increases with time. The concentration of the metabolite can be increased by increasing the number of cells plated into the tissue culture dish and the toxicity to dopamine neurons depends on the amount of metabolite accumulated in the feeding medium. The metabolism of MPTP is reduced by decreasing the number of glial cells present in the cultures.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗